I was working on a site tonight after being away from it for over three months. I came across some CSS and it took me a while to remember what it was for. I gleaned this online somewhere ages ago, but kudos and credit to the author whoever they are!

For some time I have been having problems using the ASP.NET TreeView control in Sitemaps; every time I would hover over one of the parent nodes it would jump up and down. Here's some sample markup and the CSS to fix it in Firefox: